Ingot mold



Patented June 3, 1930 PATENT; OFFICE EDMUND JAMISON KA'UFF'MZAN, OF

GIRARD, OHIO, ASSIGNOR TO VALLEY MOULD IBON CORPORATION, OF HUBBARD,OHIO, A CORPORATION OF NEW YORK INGOT MOLD Ho Drawing.

vThe present invention relates to metallurgy and more specially to ingotmolds.

Ingot molds heretofore in the art have, and now are, generally made frommolton iron, usually direct from the blast furnace, but in some casesfrom the cupola. Blast furnace iron or direct metal, does not possessthe physical characteristics of refined iron, and it sometimes happensthat direct metal ingot molds in use will develop cracks. Such cracksoccur early in the use of the mold and are referred to in the art aspremature cracks. This type of crack may be caused by the wall of theingot mold being too thin in proportion to the size of the matrix of themold, or it may be due to insuflicient annealing, or bad iron, or othercauses which result in a crack starting at the outside of the mold andgradually enlarging until it reaches the matrix of the mold, at whichtime the mold is usually ruined and not adaptable for further use.Direct metal molds or other molds unduly high in raphitic carbonsometimes tend to burn or recrack, which usually arises because thegraphitic carbon often forms in relatively large plates or flakes, theedges of which may extend to the matrix of the mold. When the mold is inuse and molten steel comes in contact with the carbon flakes, the flakesburn out and the iron starts to oxidize in the flake cavities. Theoxides form in these cavities when the mold is very hot. When the moldcools these oxides are subjected to enormous stresses and consequentlythe extraneous material in each of these carbon cavities acts as a wedgetending to open up a small insipient crack. In view of the, fact thatthe entire surface of the matrix of such a mold is composed of metalhigh in graphitic carbon, these cracks during use of the mold, extend indiflerent directions over the matrix face of the mold so that the matrixface may take on the appearance of burned or old leather. This weakensthe surface of the matrix so that erosion occurs and this is referred toas burning. when a crack starts from a carbon pocket it is called in theart a burnout crack. Such a crack will start as a Application filed July19, 1929. Serial N0. 879,580.

small incipient crack at the matrix of the mold and gradually extendthrough to the outside of themold.

To obviate the foregoing difficulties, molds have been made from steel.Steel molds, however, are unsatisfactory for the reason that steel moldsinvariably warp due to the heat of molten steel poured into the molds.When a mold warps the ingot connot be stripped from the mold.Furthermore, if in pouring the stream of molten steel strikes the sideof a steel mold so as to heat the same up to substantially the heat ofthe molten steel, the steel ingot will weld to the side wall of thesteel mold in view of the fact that the steel mold is of substantiallythe same metal as the molten metal from .which the ingot is made.

The present invention overcomes the difli culties of the prior art, andresides in mixing direct metal from a blast furnace (containing usuallyfrom 3.75% to higher per cents of carbon) or metal from a cupola (whichusually contains from 3.0% to higher percentages of carbon) with steelcontaining from .10% to .40% of carbon. The molten steel and the directmetal are, according to the present invention mixed after the moltenmetals have left the fur naces. These mixed metals result in a productwhich is different from the mixture. formed by introducing scrap steelinto a cupola or air furnace, iron, and melting the metals therein.Where steel scrap is introduced into 9. cu-' pola, or air furnace, boththe pig iron and the steel scrap are materially injured throughcontamination with the impurities in the fuel or'fuels used for melting.Further, the melting processes used are oxidizing in character, thustending to introduce oxidation products and other refractory dirtparticles picked up from the furnace linings. In. addition, it isextremely difficult to obtain and reproduce the exact chemicalcompositions and physical characteristics required due to variations ofthe raw materials, and melting variations of the difl'erenantiypes offurnaces used, or even been together with pig erent furnaces of the sametype.

On the other hand, pig iron used in the molten state direct from theblast furnace,

known in the art as direct metal is a product made from virgin rawmaterials and by a combination of powerful reducing chemical reactionswithin the blast furnace. More exact mixtures from the standpoint ofchemical compositions and physical characteristics may be made, as thecomposition of the direct pig iron and molten steel may be pre-checkedand then mixed in such relative proportions as will yield a resultantmixture with the exact chemical and physical characteristics desired. Asa result of the factors as outlined above, the mixed metals produce anovel alloy of direct metal and steel peculiarly adapted to' resistpremature cracking of ingot molds, or other heat resistant castings, duenot only to the better control of the amount of graphite carbon, butalso to the better conformation, distribution and flake size of thegraphite embedded in the metallic matrix, which matrix has beenmaterially strengthened by the steel addition. The present metal,therefore, does not substantially lose the desirable characteristics ofdirect metal, but does gain very materially in physical strength fromthe steel addition due to the improved eutectic. This obviates erosion,burning out and cracking which, as above explained, are liable to occurin direct metal molds.

The mixture of steel and iron according to the present invention, mayvary from 5% of molten steel in the total mass, to large per cents ofsteel, dependent somewhat upon the amount of carbon in the direct metaland also upon the use to which the mold is to be ut.

ccording to the present invention, it is desirable to obtain the moltensteel from the same source as directmetal is obtained. In other words,preferably, part of the direct metal from the blast furnace is convertedinto steel in a Bessemer converter, an

. open hearth,'an electrical furnace, or other known means in the art toproduce steel. This converted portion of the run of the blast furnace isthen mixed directly with the remaining portion of the direct metal fromthe blast furnace or cupola, thereby producing the molten metal to beused to cast ingot molds in accordance with the present invention.

Molds made in accordance with the present invention retain all theadvantages of molds cast from direct metal or cupola metal plus theaddition of added physical strength and consequently such molds do nottend to warp as do the steel molds referred to and they do not tend to"weld to the steel ingot, as is one of the diificulties of a steel mold;neither do, they crack as readily as direct metal molds. y 4 v The.present method maybe carried out in such manner as to only very slightlyincrease the cost of production while at the same time greatlyincreasing the life of the mold so that in the end molds in accordancewith the present invention are much more economical than direct metalmolds. In other words, the slight additional cost of production is morethan exceeded by the economy due to the increased life of the novelmold.

As a further development of the present invention, it may be desirableto cast the molds in such manner that the steel content adjacent thematrix wall of the mold will be higher than the steel content on theoutside of the mold. This mold construction increases the stren h of themold over that portion which is su j ected to the most severe strainsand at the same time the metal which supports the inner wall has theadvantages of heat absorption and slow radiation which is desirable iningot molds.

One method by which the steel content adjacent the matrix wall may beincreased is to rapidly rotate the set-up for casting the ingot mold,after the practice known in the art as centrifugal casting, and duringwhich time the direct metal is poured into the setup. This causes thecast iron or direct metal to be thrown outwardly to form the outsideportion of the mold. After a sufficient amount of direct metal has beenintroduced into the set-up to makea substantial mold wall portion, themolten steel is poured around the core bar, which steel will unite withthe direct metal forming the outside of the mold and will mingle withthe same so as to form a continuous body comprisingthe walls of themold. This body will have a large proportion of direct metal' on theoutside and with a large proportion of steel onthe inside adjacent thematrix. Such molds are very' useful in the metallurgy art, andparticularly for use in casting ironferrous ingots.

Having described my invention, I claim:

1. An ingot mold with the walls thereof comprising direct metal castiron and steel.

2. An ingot mold with the body thereof comprising an alloy of directmetal high in carbon combined with a small proportion of steel low incarbon.

3'. An ingot mold with the walls thereof comprising an alloy of castiron containing not less than three per centum of carbon and steelcontaining not more than four tenths of a per centum of carbon.

4. An ingot mold having mold walls comprising a physical mixture of castiron and steel.

5. An ingot mold having mold walls comprising an iron alloy of a largeproportion of direct cast iron and a small proportion of steel.

6. ingot mold having mold walls comprising direct cast iron, and steelwith the proportion of steel being higher adjacent the matrix of themold than adjacent the outer surfaces ofthe mold.

7. An ingot mold having-mold walls comprising cast iron and steel withthe proportion of steel being highest adjacent the matrix and with theproportion of cast iron being highest adjacent the outer surfaces of themold.

8. An ingot mold having body walls comprising substantially steeladjacent the faces of the matrix walls and substantially cast ironadjacent the faces of the outside walls.

9. As an article of manufacture, an ingot mold member having a portionadapted to contact with molten steel when said member is in use, saidmember comprising an alloy of cast iron and steel.

EDMUND JAMISON KAUFFMAN.

